Component checking circuit for burner control apparatus



JNVENTOR. JOHN M. WILSON HTI'ORNE) 2 Sheets-Sheet 1 WILSON J. COMPONENT CHECKING .CIRCUIT FOR BURNER CONTROL APPARATUS Jan. 9, 1951 Filed Aug. 9, 1948 Jan. 9, 1951 J. M. wlLsoN 2,537,292

COMPONENT crmcxmc CIRCUIT FOR BURNER CONTROL APPARATUS,

Filed Aug. 9, 1948' 2 Sheets-Sheet 2 INVENTOR. JOHN M. WILSON.

Patented Jan. 9, 1951 COMPONENT cnncmc cmonrr For; f.

BURNER CONTROL APPARATUS.

John M. Wilson, Minneapolis, Minn; assignor r to Minneapolis-Honeywell Regulator Company, Minneapolis, Minn., a corporation of Delaware? Application August 9, 1948, Serial No. 43,253

13 Claims.

This application is a continuation in part of my copending application, Serial Number 731,998. filed 'March 3, 1947, for Fuel Burner Safety Control Apparatus. V

This invention relates broadly to automatic control apparatus for fuel burners and more particularly is directed to that type of burner control apparatus that will render the burner inoperative when there has been flame failure or when the device for indicating proper operation of the burner is operating falsely.

In present day fuel burner control apparatuses, it is customary to provida safety cutout device for rendering inoperative the -burner under certain conditions ofop'eration and which, when is to provide a burner control apparatus having switching means for energizing the burner and switching means for indicating properoperation of the burner with both of the switching means having contacts which" are closed when the means is operative and contacts which are closed when the means is inoperative, and having a, safety cutout device which is energized only when either one of the switching means is operative and the other is inoperative. V x

.. In accomplishing these objects, I provide a circuit for the heater of a safety cutout device in which the heater is connected in an energizing circuit with'a source of power whenever there is a flame failure or a false indication of flame. This will be understood upon consideration of the specification, claims and drawings of which:

cutout device bypassing current therethrough whenever there is a condition of operation of the apparatus that indicates no flameat the burner when there should be a flame or when there is an indication of flame at the burner and the burner should not be operating. The apparatus further provides a control which distinguishes from a condition of flame failure and a condition of false indication of flame. V v

It is therefore an object of'the present invention'to provide an improved burner control apparatus which will be shut down upon a failure I of the combustion responsive device to correctly indicate the presence or absence of flame.

A further object of the present invention is flame failure, may be reenergized and when operated .bya failure of the combustion responsive device may not be reenergized. A still further object of the present invention is to provide an improved burner control apparatus employing a safety cutout device, having aheater therefor, which will cause the heater to be energized whenever there. has been a flame failure or a false,

indication of flame and which willdeenergize the heater only when the safety cutout device has operated uponha...fl a.me failure.

Still another obiect of'ithe'fpresent invention Figure 1 is a diagrammatic showing of one particular embodiment of my invention associated with an electronic type of flame detector. This figure was originally a part of my abovementioned copending application.

Figure 2 shows diagrammatically a modification of my invention using a single secondary transformer winding for asource of power for the controls; and

vFigure 3 shows diagrammatically a different arrangement of the'showing of Figure 2.

Referring nowto Figure 1, the numerals l and 2 represent the input power lines to the subject control apparatus and to the controls which are operated by the apparatus. These power lines are connectedthrough the control apparatus to the enclosure 3 which contains therein an ignition device 4 which is operative to initiate combustion of fuel emitting from a burner 5 when the burner is energized. For indicating the presence of flame at the burner a photocell 6 is provided. Located within an enclosure 1 is a thermostatic device 8 which is used to primarily control the operation of the burner 5. The thermostatic device 8 may be seen to consist of a, bimetal actuated switch blade 9 which is operable to move into and out of engagement with an associated switch contact [0 in accordance with temperature changes in the space wherein is located the thermostatic device.

For supplying power to the main controls of the subject apparatus, a transformer I l is pro vided and this transformer may be seen to consist of a primary winding l2, which is connected to the input power lines land 2, and a pair of secondary windings I3 and M. A main control relay is indicated by the numeral I5 and this relay may be seen to consist of a relay winding l6 which is operable when energized to move a pair of switch blades l1 and 18 into engagement with a pair of associated energized or in switch contacts I 8 and 28 respectively. When the switch blade I8 is moved intoengagement with contact 28, it moves out 01' engagement with an associated' out contact 2i. These switch blades are normally biased, by means not shown, into engagement with their respective out contacts.

The numeral 22 indicates a safety cutout device and this particular cutout device comprises a heater which is operable, when there is a current flowing therethrough, to apply heat to an associated bimetallic element 24. This bimetallic element 24 is normally positioned so as to hold a pair of switch contacts 25 and 26 in engaged position and when the bimetal has been heated for a predetermined length of time by the heater 23 it will move in an upward direction and the contact 25 will be biased out of engagement with contact 26 by means not shown and into engagement with a further contact 21 by a contact 28. A reset actuator 29 is provided for putting the cutout device back in the operating condition after the bimetal 24 has been actuated by the heater 2: and this actuator is so constructed as to prevent closing or the contacts 25 and 26 until the blmetal is in its normal position and the actuator is released.

Providing energy for the flame detection portion of the subject control apparatus is a transformer 58 which has a primary winding, connected to the input power lines I and 2, and a secondary winding 52and a further secondary winding with sections 53 and 54 with a tap 55 separating the two sections. A flame detection relay is indicated by the numeral 56 and may be seen to consist of a relay winding 51, which is bypassed by a filter condenser 58, and which is operable to move a pair or switch blades 60 and 52 from engagement with their associated deenergized or out switch contacts 6| and 63, respectively, when the winding becomes energized. These switch blades are normally biased, by

'means not shown, in engagement with the out contacts. When the switch blade 68 is moved into the energized position it engages an energized or in switch contact 58. Controlling the energizing current flow through the relay 56 is an electron discharge device which may be seen to consist of an anode 66,a control electrode 61, and a cathode 68 which is heated to be electron emissive by a filament heater 69 connected to the secondary 52. Located on the input oi. the discharge device 65 is a limiting resistor 18 as well as a phase shifting control network which includes condenser II and resistor 12 as well as resistor 13 and condenser [4. A further resistor I5 is associated with the circuit leading to the photocell 6 and acts as a current limiting resistor. This flame detection circuit is of the type completely described in my copending application, Serial Number 465,476, filed November 13, 1942, for "Control Device, now Patent No. 2,448,503, granted August 31, 1948.

Operation of Figure 1 4 mostatic device 8 will not be indicating a need for operation of the burner.

Assume that the space wherein is located the thermostatic device 8 has cooled so that the bimetallic blade 9 will be moved into engagement with contact ID to initiate the completion of an electrical circuit to the burner control relay II.

.This energizing circuit may be traced from the left-hand terminal of the secondary winding l8 through conductors 88 and 8|, relay winding i6, conductor "83, switch contact 6|, switch blade 60, conductor 85, secondary l4, conductor 86, heater 23, Qconduc'tor 81, switch contacts 26 and 25, conductor 88, switch blade 8, switch contact [8, and conductor 89 to the right-hand terminal of the secondary [3. With current flowing through the burner control relay winding l6 the switch blades i1 and I8 will be-moved into engagement with their associated contacts l9 and 28 respectively. When the switch blade i 8 engages contact 28 a holding circuit is established for the relay I! which is independent of the secondary l4 and the heater 23. This holding or maintaining circuit may be traced from the left-hand terminal oi! the secondary l3 through conductor 86, conductor 6|, winding l6, switch contact 28, switch blade 18, conductor 96, switch contacts 26 and 25, conductor 68, switch blade 9, switch contact In and conductor 88 to the right-hand terminal of the secondary l3.

While the relay I5 is maintained energized by circuit independent of the secondary l4 and the heater 23,the heater 23 is maintained in an energizing circuit that may be traced from the lefthand terminal of the secondary i4 through conductor 86, heater 23, conductors 81, and 88, switch blade i6, switch contact 26, conductor 83, switch contact 6i, switch blade 58, and conductor back to the right-hand terminal of the secondary l4.

The movement of the switch blade I'I into engagementyith switch contact I! on the burner control reay i5 results in the energization of the ignition device 4 and the burner 5. This energiz'ng circuit may be traced from the input power line I through conductor 9|, switch contact i8, switch blade ll, conductor 82, switch contact 6!, switch blade 62, conductor 83, ignition device 4, and conductor 64 to the other input power line 2. The energizing circuit for the burner motor may be traced from the input power line I through the conductor 9|, switch contacts l9, switch blade ll, conductor 82, conductor '85, burner 5, and conductor 86 to the other input power line 2.

; With the ignition device 4 energized and the burner motor 5 energized flame or combustion should be initiated at the burner'and this flame will be detected by the photocell 6.

In considering the operation of the flame detection circuit of' the subject control reference should be made to my copending applcation, Serial Number 465,476, for Control Device," mentioned above, for a fullunderstanding of the operation of this circuit. Briefly, when there is no flame detected by the photocell 6 it is desired that the control relay 56 be in the deenergized position as, it is shown on the drawing. This will mean that the electron discharge device 65 will not pass suflicient current to energize the relay 56. tively non-conducting, a phase shifting or biasing network has been provided for maintaining the control electrode 61 negative with respect to the cathode 68 during the conducting half-cycle of the power supply. This biasing network or phase To maintain the discharge device 65 efl'ecshifting network includes a circuit that may be traced from the tap 55 of the secondary winding through a conductor I III to the cathode 68 and from the cathode 68 through a conductor H9, resistor I2, condenser II, conductor 6, condenser conductor H4, resistor I3, and conductors-I I3 and III back to the left-hand terminal of the secondary section 53. It will be noted that the control electrode 61 is connected to the conductor H6 which joins condensers II and 14 by a current l miting resistor I0. With the control electrode 61 and cathode 68 connected into the last traced circuit and by properly selecting the values of the resistors I2 and I3 and condensers II and I4 it is possible to have the controlelectrode 6'I biased negatively with respect to the cathode 68 during the conductive halfcycle of the power supply. This negative bias on the control electrode 61 will maintain the current flow in the dscharge device 65 below that value necessary to cause'energization of the relay III, conductor l2l, photocell 6, conductor I24.

resistor I5, conductor I28, conductor H6. condenser II, resistor I2, conductor H9 and conductor H8 to the tap 55 on the secondary winding. With the control electrode 61 biased less negative than before the current flow through the discharge device 65 will be sufficient to energize the flame detection relay 56 and this energizing circu t may be traced from the right hand terminal of the secondary section 54 through the relay winding 51, conductor I09, anode 66. cathode 68, and conductor H0 to the tap of the secondary winding.

When the flame detection relay 56 becomes energized. the winding 51 will move the switch blades 60 and 62 into the ener ized position. When the switch blade 62 moves out of engagement with switch contact 63, the energizing circuit to the ignition device 4 is interrupted and the ignition device will remain inoperative until such time as the switch arm and contacts are again in engagement. When the switch blade moves out of engagement with switch contact 6|, the circuit through the heater 23 of the safety cutout device 22 is interrupted and no current will flow through the heater. This will mean that if the operation of the flame detection relay 56 occurs within a predetermined time the heat from the heater 23 will be insufficient to cause the bimetal to be warped from its normal position to allow opening of the switch contacts 25 and 26. I,

The apparatus is now in the operating condition with both the burner control relay I5 and the flame detection relay 56 in the energized position. Further, the safety cutout device 22 is completely deenergized with no current flow passing through the heater 23 of this cutout device.

As soon as the heat from the burner 5 has satisfied the temperature condition for which the I thermostatic device 8 is set to operate, the bimetal switch blade 9 will be moved out of en-" gagement with the associated contact I 8. The

movement from the contact [6 by the blade 8 6 results in opening of an electrical circuit through the burner control relay l5 and this relay will become deenergized. When the relay becomes deenergized, the switch blade II will move out of engagement with the associated switch contact Hi to open the energizing circuit for the burner motor 5 so that the burner will become deenergized. When the burner becomes deenergized, the flame will be extinguished and the flame detection relay will become deenergized with the rectifying action of the photocell 6 no longer affecting the biasing of the control electrode 61 of the discharge device 65. With both the flame detection relay 56 and the burner control relay I 5 in the deenergized position, the apparatus will be back in the position that is shown in thedrawing. The apparatus is now in condition for another operating cycle upon the subsequent closing or call for burner operation by the thermostatic device 8.

Operation uponflame failure Assume now that the apparatus hasbeen 'operating normally with both the burner control tion suddenly ceases due to somefaulty operation in the fuel line or the burner. With the stopping of the combustion, the photocell 6 will not detect the presence of combustion and the rectifying action of the photocell will no longer be effective to bias the control electrode 61 less negative with respect to the cathode so that the current flow through the discharge device will be insufficient to maintain the flame detection relay 56 in the energized position. With the deen rgization of the relay 56, the switch blade 62 will move into engagement with switch contact 63 to complete the energizing circuitto the ignition device 4 so that the apparatus will attempt to reestablish combustion. The switch blade 61l-v will be moved into engagem nt withswitch contact GI and this movement will result in the completion of an electrical circuit through the safety cutout heater 23 and this circuit may be traced from the left-hand terminal of the secondary l4 through conductor 86, heater 23, conductorBI, switch contacts 26 and 25, conductor 81, conductor 90, switch blade l8, switch contact 20, conductor 83, switch contact 6|, switch blade 60, and conductor back to the right-hand termi-- 'nal of the secondary l4. main energized until such time as the ignition device 4 reestablishes combustion or until the bimetal 24 is warped to such a position as to allow separation of the switch contacts 25 and 26.

If the combustion is not reestablished and the switch contacts 25 and 26 separate, the switch contacts 28 will move into engagement with switch contact 21 so that a circuit may be traced through the indicating lamp 36. This circuit may be traced from the left-hand terminal of the secondary I3 through conductor 80, conductor- I60, indicator 30, conductor Hll, switch contacts 21' and 28, conductor 88, switch blade 8 switch contact [0, and conductor 89 to the righthand terminal of the secondary I3. The circuit through the indicator 3!! will give notice of the fact that the safety cutout device is in the deenergized, position. When the switch contacts '25 and 26'sepa'rate'd, the-holding circuit for the This circuitwill re- Marissa out of engagement with the switch contact 20, the electrical circuit that was last traced through the safety cutout heater 23 is also broken so that the heater 23 will no longer be supplying heat to the bimetal 24. As long as there is no heat applied to the bimetal 24, it will tend to move back to its normal position as it cools so that subsequent depressing of the actuator 29 will result in the bimetal moving back to the position shown on the drawing so that release of the actuator will cause the end of the bimetal to force the contact 25 into engagement with contact 25.

Depressing of the actuator 29 will recomplete the energizing circuit for the burner control relay l and the relay will become energized to once again attempt the establishment of combustion by the burner 5. If combustion is not established, the continued, flow of current through the safety heater 23 'will'result in the subsequent warping of the bimetal 24 and the shutdown of the current when the flame failure occurred.

Obviously in the event that there is a failure of the apparatus to initiate combustion upon the closing of the thermostatic device 8 the apparatus will be shut down in the same manner as when the apparatus is brought into operation by resetting of the safety cutout device upon a flame failure. It will further be noted that as long as there is a flame failure or combustion failure, it is possible to initiate operation of the burner motor 5 by depressing of the actuator or reset 29 as the heater 23 is deenergized when the contacts 25 and 26 open.

Operation upon jalse indication of flame the contacts 21 and 28 will be in engagement and the circuit to the indicator 30 will be completed so that there will be an indication of faulty operation of the system.

With a shutdown upon a false indication of ilame, it will be impossible to reset the safety cutout device 22 by the actuator 23 until such turb this energized circuit.

Assume for the moment that the burner contrcl apparatus has been operating properly and there has been combustion at the burner 5. Assume further that the thermostatic device 8 is no longer calling for operation of the burner and the blade 9 moves out of engagement with switch contact 10 to open the energizing circuit for the burner control relay I5. With the energiz.ing circuit for the relay '55 open, the switch blades I8 and I! will move out of engagement with their associated contacts so that the burner 5 will be shut down. Should therefibej any faulty operation in the flame detection circuit which would maintain an energizing current. flowing through the flame detection relay 56, the relay will remain in the energized position so that the switch blade 50 is engaging switch contact 59 even though the burner 5 is not operative. This is now a condition where the flame detection relay is indicating proper operation of the burner while the burner, in fact, is not in operation.

My apparatus provides for a shutdown of the control apparatus by comp eting an energizing circuit to the safety cutout device heater 23; this cncrgl ing circuit may be traced from the lefthand terminal of the secondary [4 through con-- ductor 8E, heater 23, conductor 81, conductor 90,

switch blade i8, switch contact 2!, conductor 91',

As soon as the fault causing the false operation of the flame detection relay 58 is removed, the

switch blades 80 and 62 will be moved to the deenergized positionso that the energizing circuit for the heater 23 will be interrupted and the same will no longer be maintaining the blade 24 in the warped position. As soon as the bimetal 24 is cooled sufficiently, it will be possible to reset the cutout device 22 in the normal manner and the apparatus will be brought into operation upon the subsequent closing of the thermostatic device 8.

Figure 2 The apparatus shown in Figure 2 is a modification of the basic circuit disclosed in Figure 1 and utilizes a single transformer secondary winding as a source of power for accomplishing the type of control accomplished by Figure 1. The apparatus disclosed in this figure has eliminated reference to the use of an ignition device and an alarm or indicator as it is believed obvious as to how these would be incorporated in the subject figure. In Figure 2 the numeral 200 represents a burner of any desired type and this burner is rendered operative orinoperative ,in accordance and 28 separate it is im ossible to initiate operation or energization of the burner control relay l5 upon the subsequent closing of the thermostatic device 8. It will be noted that once again with the operation of a thermostatic switching device 20| which may be located in any desired position to indicate the need for operation of the burner 200.

in the enclosure 202 to initiate operation of the burner 200.

The thermostatic device 20| may be seen to cons st of a bimetalically operated switch blade 203 which is operative upon the cooling of the device to move into engagement with a switch contact 204.

Applying energy to the controls located in the housing 202 is a transformer 205 which has a primary winding 26 which may be connected to any s"itabe source of power and a secondary winding 20! which is tanned at 208. The burner control relay for the subject apparatus isindicated by the numeral 210 and may be seen to consist of a relay winding 2!! and a pair of switch blades 2 l2 and H3 which are moved into engagem nt with in switch contacts 2 and H5 respectively when the winding 21! becomes energized. When the winding 2| I is deenergized,

the switch blade is normally biased into engagement with an associated out contact 2 l5 by means notshown.

A photocell 2 I1 is provided for viewing, the combustion at the burner 200 and is operative through appropriate circuits lo at d in the block indicated at M8 to energize a flame detection relay 2| 9. The electrical flame detection circuits indicated by the block 2| 8 may well be of the type disclosed in Figure 1. The flame detection relay The-operation of the thermostatic device 20 I is effective to cause the controls with- 2I0 may be seen to consist of a relay winding 220 which is operative to-move a switch blade 22l from engagement with a deenergized or out contact 222, where it is biased by means not shown,

and intoengagement with an energized or in the contacts 221 and 228 have been opened and this actuator is of the type that will not permit closing of the contacts 221 and 228 unless the bimetal 226 is back in its normal position.

Operation of Figure 2 The apparatus, as shown in Figure 2 of the drawing, is in the deenergized position with the burner 200 inoperative and the thermostatic device 20I not indicating the need for operation of the burner. In the event that the space where the thermostatic device 20! should cool, the bimetallic switch blade 203 will be moved into engagement with its associated contact 204 and an electrical circuit will be completed to the burner control relay 2 l0. This energizing circuit maybe traced from the upper terminal of the secondary 201 through conductor 235, switch blade 203, switch contact 204, conductor 236, relay winding 2| I, conductor 231, switch contacts 221 and 228, conductor 238, switch contact 222, switch blade 22I, conductor 239, heater 225, and conductor 240 back to the lower terminal of the secondary 201. With the energization of the burner control 2l0, the switch blade 2I3 will move into en gagement with the switch contact 215 so that an electrical circuit will be completed to the burner 200 and this circuit may be traced from the input power line 24l through conductor 242, switch contact 2|5, switch blade 2l3, conductor 243, burner 200 and conductor 244 back to the other input power line 245.

When the switch blade ,2 I2 moves into engagement with switch contact 2| 4, a holding circuit is established for the relay M0 and this holding circuit is independent of the heater 225 of the safety cutout device. The holding circuit may be traced from the upper terminal of the secondary 201 through conductor 235, switch blade 203, switch contact204, conductor 236, re-

lay winding 2, conductor 231, switch contacts 221 and 228, conductor 238, conductor 246, switch contact 2, switch blade 2I2, and conductor 241 back to the tap 208 of the secondary 201.

A separate energizing circuit is provided for the safety cut out heater 225 and this circuit may be traced from the lower terminal of the secondary 201 through conductor 240, heater 225,

conductor 239, switch blade 22l, switch contact 222, conductor 246, switch contact 2l4, switch blade M2, and conductor 241 to the tap 208 on the secondary winding. This last traced circuit will remain in existence until such time as photowith both the burner control relay 2I0 and the flame detection relay 2I8 in the energized position and the thermostatic device 20! indicating a continued need for operation of the burner.

As soon as the thermostatic device 201 no longer indicates a need for operation of the bumer, the blade 203 will move out of engagement with contact 204 and the burner control relay will become deenergized to open the energizing circuit to the burner 200. With the burner 200 no longer energized, there will not be a flame at the burner and the photocell 2" will cause the flame detection relay 2|9 to become deenergized so that the entire control apparatus will be in the position that it is shown on the drawing and will be ready for another operating cycle upon the closing of the thermostatic device 20!.

Operation of Figure 2 upon flame failure engages contact 222. 'When this occurs an energizing circuit is completed through the safety cutout heater 225 and this circuit may be traced from the lower terminal of the secondary 201 through conductor 204, heater 225, conductor 239, switch blade 22I, switch contact 222, conductor 246, switch contact 214, switch blade 2I2, and

conductor 241 to the tap 208 on the secondary winding. If combustion is not established within a predetermined length of time, the heater 225 will cause the bimetal 226 to be warped toward the right so that the contacts 221 and 228 will separate. The separation of the contacts 221 and 228 will result in the deenergization of l the burner control relay 2| 0 and the burner 200 will be shut down. Also deenergized by the deenergization of the relay 210 is the energizing circuit for the heater 225; with heater 225 deenergized it will be possible for the bimetallic element 226 to cool and move back toward its normal position so that the subsequent depressing of the reset actuator 229 willallow the bimetal to come back to its normal position and the contacts 221 and 228 will close so that the relay 2| 0 will once again become energized and cell indicates combustion at the burner 200, at

which time the flame detection relay. 2l9 will become energized so that the switch blade 22| will move out of engagement with contacts 222 to open the energizing circuit for the heater 225 traced above.

The apparatus is now in the operation position attempt to establish 200. tablished, the safety cutout heater 225 will again cause the bimetallic element to be warped to the right and the opening ofthe contacts 221 and 228 will result in the deenergization of the burner control relay 2 I0.

Obviously this type of shutdown would occur if the flame detection relay failed to indicate combustion whether the control relay 210 were energized by the depressing of the actuator 223 or by the operation f the thermostatic device 20L and the flame detection relay 2!!! have been operating properly with the burner energized and combustion at the burner the thermostatic device 20l indicating a need for burner operation. Upon the subsequent satisfaction of the thermostatic device 20L the burner control relay 2l0 will become deenergized In the event that combustion is not esonce at theburner.

lower terminal of the secondary 201 through the conductor 240, heater 225, conductor 288, switch blade 22|, switch contact 220, conductor 248, switch contact 2|5, switch blade 2|2, and conduc-' tor 241 to the tap 200 on the secondary 201. This circuit will remain energized until such time as the fault causing operation of the flame detection relay 2|8 is removed, for the same reason that the maintaining energizing circuit for the heater of Figure'l was maintained energized as long as the flame detector was operating falsely. This will mean that the heater 225 will move the bimetal 225 toward the right so that the contacts 221 and 228 will separate and it will be ass-1,292

impossible for the burner control relay 2|0 to be energized upon the subsequent closing of the thermostatic device 20L As long as the bimetal 228 is in the warped position, it will be impossible to reset or close the contacts 221 and 228.

As soon as the fault from the relay 2|! has been removed, so that the switch blade 22| engages switch contact 222, the energizing circuit for the heater 225 will be broken and the bimetal 225 will cool so that it will move back toward its normal position as it is shown on the drawing and a subsequent depressing actuator 229 will result in the closing of the contacts 221 and 228 as they come to rest on the top of the bimetal 228. The apparatus is now in a condition for normal operation so that the subsequent closing of the thermostat 20| will result in the energization of the burner in the manner discussed above.

Figure 3 The apparatus shown in Figure 3 includes the identical components provided in the showing of Figure 2 and these components all carry the same reference numerals in both of the drawings. In Figure 3 the components are associated with the secondary windin 201 in a manner slightly different than that of Figure 2 in a manner that will be understood from the following discussion.

Operation of Figure 3 When the thermostatic device 20| indicates the need for operation of the burner, the blade 203 will move into engagement with contact 204 and this will result in an energizing circuit for the burner control relay 2 0 that may be traced from the upper terminal of the secondary 201 through conductor 250, blade 203, switch contact 204, conductor 25|, relay winding 2| I, conductor 252, switch contacts 221 and 228, conductor 253, switch contact 222, switch blade 22 I, conductor 254, heater 225. and conductor 255 back to the tap 208 of the secondary 201. Upon the energization of the burner control relay 2|0, the switch blade 2|3 will move into engagement with switch contact contact 204, conductor 25l, relay winding 2, conductor 252, switch contacts 221 and 228, conductor 258, conductor 258, switch contact 2. switch blade 2|2, and conductor 251 back to the lower terminal of the secondary 201. It will be noted that in the subject circuit, the burner control relay is energized from a portion only of the secondary'201 and is maintained energized by the entire secondary vpltageswhilej' he reverse was true with the circuit of Figure 2.

The heater of the cutout device 224 wares maintained in an energizing circuit until such c time as the flame detection relay 2|8 becomes operative to indicate proper burner operation and this energizing circuit may be traced from the lower terminal of the secondary 201 through conductor 251, switch b.aoe 2|2, switch contact 2, conductor 255, switch contact 222, switch blade 22|, conductor 254, heater 225,, and conductor 255 to the tap 208 and the secondary 201. As soon as the flame detection relay 2|8 becomes operative, the switch blade 22| moves out of engagement with contact 222 to open the last traced circuit and deenergize the circuits through the heater 225. Obviously, if this circuit is not interrupted within a predetermined time, the bimetal 225 will be warped toward the right so that the contacts 221 and 228 will separate to open the energizing circuit for the relay 2|0 and this circuit will remain interrupted until such time as the reset actuator 228 is depressed and the contacts 221 and 228 are once again in engagement. This will occur upon either a flame failure occurring during normal operation or upon a failure of combustion to be initiated when the apparatus starts its operating cycle.

The operation, because of a false indication of flame by the flame detection relay 2|8, is practically identical to that of Figure 2, when there is a false indication of flame by the flame detection relay and there is no call for operation of the burner, so that the burner control relay 2 I0 is in the deenergized position. When this occurs a circuit may be traced to the heater 225 from the lower terminal of the secondary 201 through conductor 251, switch blade 2|2, switch contact 2|8, conductor 258, switch contact 223, switch blade 22 conductor 254, heater 225, and conductor 255 tothe tap 208 on secondary 201. This circuit will remain energized .until such time as the fault causing the false operation of the flame detection relay 2 8 is removed. This will prevent the closing of the safety cutofl contacts 221 and 228, as the heater 225 will maintain the bimetal 228 warped toward the right so that the contacts cannot come to rest on the top of the bimetal. As soon as the fault is removed the heater 225 will allow the bimetal 226 to cool so that it will be possible to reset the contacts 221 and 228. The apparatus is now in a condition for a normal operating cycle upon the subsequent closing of the thermostatic device 20|.

Conclusion From the foregoing it may be seen that I have provided a burner control apparatus which will be rendered inoperative in the event of a flame failure or upon a false indication of flame and that I further have provided therewith facilities for determining whether the apparatus is shut down because of flame failure or shut down because of a false indication of flame. While I 'have disclosed certain embodiments of my invention it will be obvious to those skilled in the art that various modifications are readily suggested upon a consideration of the foregoing specification and therefore I intend my invention to be limited solely by the scope of the appended claims in which I claim:

1. Control apparatus for a fuel burner, comprising in combination, a source of power, a first relay having switch contacts adapted when actuated to complete an energizing circuit to the burner, a second relay having switch contacts adapted to be actuated by means indicative of proper burner operation, a safety cutout device having an electricalactuator which when ener-' gized for a predetermined length oftime will open an associated switch, a first circuit for energizing said first relay, said first circuit including said source of power and said cutout device actuator and switch, a second circuit for maintaining said first relay energized, said second circuit including switch contacts of said first relay and said cutout device switch, a third circuit for maintaining said cutout device actuator energized, said third circuit including said source of power and contacts of said first relay when energized and said second relay when deenergized and operative to cause said cutout device actuator to open said cutout device switch to deenergize said first relay and open said third circuit unless said second relay first becomes operative to deenergize said cutout device actuator, and a fourth circuit for cont nuously energizing said cutout device actuator independently of said cutout device switch when said first relay is deenergized and said second relay is in energized position falsely indicating burner operation so that said cutout device will maintain the burner inoperative until the fault causing operation of said second relay is removed. I

2. Control apparatus for a fuel burner comprising in combination, a source of power, a first relay adapted when energized to complete an energizing circuit to the burner, said relay comprising switch contacts normally closed when the relay is deenergized and switch contacts normally closed when the relay is energized, a second relay adapted to be energized by means indicating proper operation of the burner, said second relay comprising switch contacts normally closed when the relay is deenergized and switch contacts normally closed when the relay is energized, a safety cutout device having an electrical actuator and an associated switch adapted when energized for a predetermined length of time to render said apparatus inoperative, a first circuit for connecting said first relay in energizing relation to said source of power adapted to be completed by means indicatinga need for operation of' the burner, said first circuit including said cutout device actuator and switch, and the closed switch contacts of said second relay when deenergized, a second circuit for maintaining said first relay energized, said second circuit including i said source of power and closed switch contacts of said first relay when energized, a third circuit for maintaining said cutout device actuator energized, said third circuit including said source of power, closed contacts of said first relay when energized and closed contacts of said second relay when deenergized and maintained operative until said cutout device actuator operates on said cutout device switch or said second relay indicates proper operation of the burner and said actuator is deenergized, and a fourth circuit for maintaining said cutout device actuator ener-' gized when said second relay is in operating position, said fourth circuit including said source of power, closed switch contacts of said second relay when in energized position and closed switch contacts of said first relay when deenergized.

3. In a burner control apparatus, the combination comprising, a source of power comprising a transformer winding having a tap thereon and at least two end terminals, a main control relay adapted when energized to complete an energizing circuit to the burner, said relay comprising a switch blade and in and out switch contacts, a flame detection relay adapted to be energized upon proper burner operation, said detection relay comprising a switch blade and in and out switch contacts, a safety cutout device having an actuator and an associated switch for rendering inoperative the burner when said actuator has had current flowing therethrough for a predetermined length of time, an energizing circuit for said control relay adapted to be completed by means indicative of the need for burner operation, said circuit including said cutout device actuator and switch, the switch blade and out contact of said detection relay and the end terminals of said source of power, a maintaining circuit for said control relay independent of said cutout device actuator, said maintaining circuit including the switch blade and in contact of said control relay and one end terminal and the tap of said source of power, and a circuit for maintaining current fiow through said cutout device actuator independently of said control relay whenever the burner fails to operate or said detection relay operates falsely and indicates proper burner operation, said circuit including the tap and the other end terminal of said source of power and either the switch blade and in contact of said control relay and the switch blade and out contact of said flame detection relay or the switch blade and out contact of said control relay and the switch blade and in contact of said flame detection relay.

4. In a burner control apparatus, the combination comprising, a source of power comprising a transformer winding having a tap thereon and at least two end terminals, a main control relay adapted when energized to complete an .energizing circuit to the burner, said relay comprising a switch blade and in and out switch contacts, a flame detection relay adapted to be energized upon proper burner operation, said detection relay comprising a switch blade and in and out switch contacts, a safety cutout device having an actuator and an associated switch for rendering inoperative the burner when said actuator has had current flowing therethrough for a predetermined length of time, an energizing circuit for said control relay adapte to be completed by means indicative of the nee i for burner operation, said circuit including said cutout device actuator, and switch, the switch blade and out contact of said detection relay and the tap and one end terminal of said source of power, a maintaining circuit for said control relay independent of said cutout device actuator, said maintaining circuit including the switch blade and in contact of said control relay and the end terminals of said source of power, and a circuit for maintaining current flow through said cutout device actuator independently of said control relay whenever the burner fails to operate or said detection relay is in operating position and falsely indicating proper burner operation, said circuit including the tap and one end terminal of said source of power and either the switch blade and in contact of said control relay and the switch blade and out contact of said flame detection relay or the switch blade and out contact of said control relay and the switch blade and in contact of said flame detection relay.

5. In a condition control apparatus; a power source comprising a transformer having a plurality of secondary windings; a safety switch device having an electrical actuator and switch contacts; first and second relay means each having a plurality of switch contacts; condition sznsing means operable upon a need for a change in a condition to connect said first relay means in an energizing circuit with said power source through said safety switch device actuator and switch contacts and certain of the contacts of said first and second relay means; means for holding said firstrelay means in an energized circuit including one windinglof said power source, said condition sensing means, switch contacts of said first relay means, and switch contactsof said safety switch device; means for continuing theenergization of the actuator of said safety switch device including a further winding of said power source and certain of the switch contacts of said first and second relay means; control means for a condition changing means made operative upon energization of said first relay means; means responsive to the proper operation of said last named means to cause energization of said second relay means; means for deenergizing said safety switch actuator upon energization of both said first and second relay means, means including said safety switch device and certain of the switch contacts of said first and second relay means for deenergizing said first relay means and the actuator of said safety switch when said second relay means fails to be energized, and further means including certain of said switch contacts of said first and second relay means for rendering inoperative only said first relay means when said second relay means is falsely indicating proper operation of said condition changing means.

6. In combination, a source of power having at least a pair of secondary transformer windings, a first relay means having in and out contacts, second relay means having in" and "out contacts, an electrically operable cutofi device having an electrical time delayed actuator and switch contacts, means including said cutoff device and an out" contact of said second relay means for connecting said first relay means in an energizing circuit to both of said secondary windings of said power source connected in series, means including an in contact of said first relay means and the switch contacts of said device connecting said first relay means in a holding circuit with one of said windings of said source of power, means including an in contact of said first relay means and an out contact of said second relay means serially connected for maintaining an electrically conducting circuit through said cutoff device actuator with the other winding of said source of power so that after a predetermined time delay said cutoff device actuator will render said switch contacts of said device inoperative, means for energizing said second relay by said power source to render said last named circuit inoperative by the opening of said out" lay means, and further means including an in contact of said second relay means and an out" contact of said first relay means serially connected for rendering said cutoff device actuator continuously energized when said first relay means is deenergized and said second relay means is energized to maintain said switch contacts of contact by said second re- 16 said device open and said firstrelay means inoperative.

7. Burner control apparatus, comprising in combination, first electrically operated switch means for initiating operation of the burner, second electrically operated switch means for indicating proper operation of the burner, a safety cutout device comprising normally closed switch contacts and an electrical actuator therefor which is operative when energized for a predetermined length of time to open said contacts and render the apparatus inoperative, means including said contacts when closed, said first switching means when energized and said second switching means when deenergized for connecting said actuator in a first energizing circuit which when operative for a predetermined length of time will become deenerglzed upon the separation of said contacts, and means including said first switching means when deenergized and said second switching means when energized for connecting said actuator in a second energizing circuit independent of said contacts which will remain energized after actuation of said contacts of said cutout device.

8. Burner control apparatus, comprising in combination, temperature responsive means for completing an electrical circuit and initiating operation of the burner, electrically operated switch means for indicating proper operation of the burner, a safety cutout device having switch contacts and an actuator therefor which is operative when energized for a predetermined length of time to open said contacts and render said apparatus inoperative, a, first energizing circuit for said actuator, said circuit including said cutout device contacts, said responsive means when completing an electrical circuit to the burner and said switch means when deenergized and adapted to be rendered inoperative upon separation of said cutout device switch contacts or upon the energization of said switch means, and a second energizing circuit for said actuator independent of said cutout device contacts, said second circuit including saidresponsive means when not completing said circuit to the burner and said switch means when energized and operative to maintain said actuator continuously energized until said switch means is deenergized.

9. In a control apparatus for a fuel burner, the combination comprising, first electrically operated switch means for initiating operation of the burner, second electrically operated switch means for indicating proper operation of the burner, both of said switch means having contacts closed when energized and further contacts closed when deenergized, a safety cutout device having an electrical heater therefor which when, energized for a predetermined length of time will open a pair of switch contacts and cause said cutout device to render said apparatus inoperative, electrical circuit means including said first switch means when energized, said pair of switch contacts, and said second switch means when deenergized for energizing said heater, means for deenergizing said heater including said first and second switch means when energized, and further electrical circuit means for continuously energizing said heater independently of said pair of switch contacts when said second switch means is falsely indicating proper burner operation, said means including said first switch means when deenergized and said second switch means when energized with said further means maintaining said heater energized until said second switch means is deenergized.

10. In a control apparatus for a fuel burner, a temperature responsive device, a safety switch device having a switch and an electrical actuator with a time delay and reset means therefor which can put said switch in operative position only when said actuator is inoperative, a power source comprisinga transformer with a plurality of secondary windings; first and second relay means each having a plurality of switch-contacts; means includingsaid temperature'responsive device, at,

least two of the secondary windings of said power source, said safety switch device actuatonand certain of'the switch contacts of said first and second relay means for serially connecting said first relay means in an energizing circuit; burner control means adapted upon the energization of said first relay means to render the burner operative, combustion responsive means associated with said second relay means and adapted to' cause energization thereof upon proper operation of the burner, means including certain of the switch contacts of said first and'second relaymeans for rendering said safety switch device actuator inoperative when said first and second relays are energized, circuit means rendering said actuator inoperative upon energization thereof v at least a pair of secondary-transformer windings,

. ,a first relay having switch contacts, a cutoff device having an electrical timedelayed actuator and switch contacts, a second relay means having switch contacts, means connecting said first relay and said actuator in a series circuit to said secondary windings so that said first relay will be energized only when said actuator and both of said windings are intact, means including switch contacts of said first relay means when energized and said cutoff device switch contacts for maintaining said first relay connected in a maintaining circuit to one of said secondary windings, means including switch contacts of said first relay when energized and switch contacts of said second relay when deenergized for maintaining said actuator in an energizing circuit with said other winding until said second relay becomes enersized or said actuator is effective to open the switch contacts of said device and deenergize said first relay, and means for continuously maintaining said actuator energized including switch contacts of said first relay when deenergized,switch contacts of said second relay when in energized position and said other secondary winding until said second relay is moved to deenergized position.

12. In a burner control apparatus, the combination comprising, a main control-relay having switch contacts which when actuated are of said device in Al 11. In combination, a source of power having l8 adapted to complete an energizing circuit to th burner, a source of power, energizing and holding circuits for saidreiay having a common por-' tion which includes said source of, power and means for indicating aneed for burner operation, a manually reset safety'cutoff device having an electrical actuator therefor which when energized a predetermined length of time will actuate a pair of cutoif contacts to prevent operation of said main relay, a flame detection relay 1 having switch contacts for indicating properjoperation of the burner, first circuit means for energizing said cutoff device actuator until said cutout contacts render said first relay inoperative, said first circuit means including said source of power, switch contacts of said flame detection relay when deenergized, and said cutout contacts, and a second circuit means independent of said cutout contacts but including said source of power and contacts of said flame detection relay for continuously energizing said cutout device actuator when said main control reay i's deenergized and said flame detection relay is in energized position and falsely indicating burner operation, said second circuit means-remaining energized after actuation of said cutout device and preventing burner operationuntil the fault causing operation of said flame detection relay is removed. 7

13, In a control apparatus for a fuel burner, a

temperature responsive device, means actuated by said temperature responsive device for completing an energizing c rcuit to thevfuel burner,

a combustion responsive device having a first pair of switch contacts which are actuated upon the occurrence of combustion at the burner and a second pair which are actuated when no. combustion is present, a reset safety switch having an actuator therefor with cutoutv contacts connected in series circuit with said first named means and which when actuated are operable to deenergize said first named means upon failure of operation of said combustion responsive device, ,means connecting the second pair of said combustion responsive device switch contacts in a series energizing circuit with said safety switch actuator to disconnect said safety switch actuator and maintain said first named means operative upon proper operation of the-burner, and I further means connectingsaid safety switch at:- tuator in an energizing circuit independently of said temperature responsive device and said cut-' out contacts to render said safety switch actuator operative when said combustion responsive device is falsely indicating combustion to thereby maintain said first named means inoperative, said last named means comprising the first pair of said combustion responsive device switch contacts.

JOHN M. WILSON.

REFERENCES CITED The following, references are of record in the file of this patent:

Tate Sept. 2. 1941 

